1. Field of the Invention
The present invention relates to a method and an apparatus which are suitable for applying sealing materials to predetermined portions of automotive vehicle bodies, such as seams of component members of the bodies.
2. Discussion of the Prior Art
Usually, bodies of automotive vehicles are formed by joining many component members (generally formed by pressing), for example, by spot welding. To ensure a high degree of fluid-tightness of the vehicle bodies, it is necessary to apply a suitable sealer to the seamed portions of the component members of the bodies.
In light of the above need, the assignee of the present application proposed a sealing method and apparatus for automatically applying a sealing material to vehicle bodies, as disclosed in Laid-Open Publication 60-143876 (published in 1985) of an unexamined Japanese Patent Application. In this proposed method and apparatus, there is provided a single sealing station at which the sealing material is applied to all portions of the vehicle body that should be sealed. Described more specifically, sealing robots are disposed on transversely opposite sides of the vehicle body, and on longitudinally opposite sides of the body. The sealing robots disposed on the transversely opposite sides of the vehicle body are adapted to apply the sealing material to right and left doors of the vehicle, portions of the vehicle body near the doors, and outer side surfaces of an engine hood and a luggage compartment door. The sealing robot disposed on the front side of the vehicle body is adapted to apply the sealing material to the inside of the front portion (engine room) of the vehicle body which is covered by the engine hood. Further, the sealing robot disposed on the rear side of the vehicle body is adapted to apply the sealing material to the inside of the rear portion (luggage compartment) of the body covered by the luggage compartment door.
The sealing robots disposed on the front and rear sides of the vehicle body to seal the insides of the front and rear portions of the body inevitably tend to be large-sized, and are considerably difficult to accurately control during the sealing operations. Further, these sealing robots are required to be positioned a suitable distance above the sealing station, in order to avoid an interference of the robots with the vehicle body, when the vehicle body is brought into the sealing station. This arrangement requires a rigid and massive frame for supporting the sealing robots above the sealing station, resulting in an increase in the cost of the sealing apparatus as a whole. Further, the same arrangement requires difficult procedures for adjustment and maintenance of the sealing robots.